| 摘要 |
PROBLEM TO BE SOLVED: To maintain a proper surface pressure at rolling contact portions between the inner surfaces of input and output discs 2, 5 and the peripheral surfaces of power rollers 6, 6 under normal conditions and secure the surface pressure at each of the rolling contact portions even in the event of failure. SOLUTION: A pressing force control valve 56 controls hydraulic pressure introduced into a pressing device 23a. A differential pressure between the hydraulic chambers 63a, 63b of an actuator 10 for displacing a trunnion 7 is taken out by a differential pressure takeout valve 64 and introduced into either of the first and second pilot parts 60, 61 of the pressing force control valve 56. A hydraulic pressure for correction which a gear ratio controller 76 calculates according to gear ratio or the like is introduced into the third pilot part 62 of the pressing force control valve 56. Under normal conditions, the hydraulic pressure introduced into the third pilot part 62 lowers the valve-opening pressure of the pressing force control valve 56 to a necessary value. In the event of failure, the valve-opening pressure is set to match the hydraulic pressure introduced in either of the first and second pilot parts 60, 61, so as to prevent excessive slip at the rolling contact portions. COPYRIGHT: (C)2004,JPO |
